There are numerous known types of optical systems employing mirrors for obtaining wide fields of view for use, typically in telescopes, examples of which include the Schmidt system which is configured from a combination of both refractive and reflective elements and the Schwarzschild system which is formed with both concentric and flat field forms. Other types of reflective three mirror and four mirror systems are also well known; however, they provide less than adequate imaging properties over a planar focal surface for certain applications. The best known performing two mirror telescope is the aplanatic Cassegrain system which is corrected for spherical aberration and coma, but exhibits considerable astigmatism as well as curvature of field which is typically limited to 1.degree. in diameter. The addition of a third mirror makes it possible to correct more third order aberrations, but usually there still exists a field of view which is less than 10.degree. in diameter, and the same central obscuration that is characteristic of two mirror systems. All refractive multielement systems avoid the problem of obscuration and may provide a relatively large field of view but are nevertheless severely limited in the spectral range of operation. The spectral range that can be covered is made almost limitless by using all reflective elements; however, this normally introduces obscurations which degrade optical performance by introducing vignetting of the images, and by the reduction in spatial resolution due to additional diffraction.